1. Field of the Invention
The present invention relates to compositions useful in the control of fertility, and also to composition useful in the inhibition of malignant cell growth and in the control of diseases which accumulate cells such as macrophages, polymorphonuclear leukocytes, platelets, etc., at the disease site. More specifically, it relates to novel chemical compositions and pharmaceutical formulations comprising a weakly basis amine or a nitrogen-containing heterocyclic compound having a pK of from 3.5 to 8, incorporating a hydrophobic moiety.
The present invention also relates to novel weakly basic amine compounds.
Lysosomotropic substances are substances which are selectively taken up by lysosomes, which are present in most animal cells. The property of lysosomotropism is thus useful in the preparation of therapeutic agents since these agents can enter the lyosomes preferentially and exert their biological influence by disrupting the lysosomes. They also can be coupled with active drugs and, following preferential uptake by lysosomes, can be hydrolyzed within the lysosome with release of the active drug at the target area.
Lysosomes are membrane-bound organelles containing a variety of hydrolytic enzymes that would be cytotoxic if released within the cell. Lysosomes function to destroy invading microorganisms, which is accomplished by phagocytosis; to disposed of exhausted cell components; and to break down nutrient materials within the cell, which is accomplished by endocytosis. When the nutrient material is dissolved in water, the process is called pinocytosis. A common aspect of all three processes is that the cell's outer membrane engulfs the microorganism, particle, or liquid droplet, forming a membrane-bound vesicle that is internalized and is then fused with a lysosome for chemical treatment. Normally, at all times the lysosomal contents are separated from the cytosol by a membrane.
A significant feature of the interior environment of the lysosome is its acidity. The intralysosomal pH is between 3 and 5, compared to a normal cell interior envionment pH of about 7, i.e., neutral. The importance of this feature will be described further below.
If the lysosome membrane is ruptured, the lysosome then pours out into the remainder of the cell in which it is contained, its contents of powerful hydrolytic enzymes, which soon results in destruction of the cell itself. This action can be used to therapeutic advantage in a number of ways, as will be detailed below.
The lysosomal membrane is a bilayer membrane sheet, e.g., like that formed by phospholipids such as lecithin. The molecular units from which the bilayer membrane is formed are composed of a lipophilic portion at one end, comprising two parallel elongated segments, and at the opposite end, a hydrophilic portion. The molecular structure of these units enables them to form stable bilayers of indefinitely large extension. This is in contrast to the molecular structure of detergents which, while they have opposing lipophilic and hydrophilic portions, are characterized by a lipophilic portion comprising only one elongated segment. Detergents cannot form large stable bilayers, but only small ones called micelles which have small radii of curvature. Consequently, when a detergent is introduced into the bilayer membrane of a lysosome, which is readily accomplished because of the similarity in structure, the detergent units disrupt the lysosome membrane and ultimately result in its rupture.
However, it is not practical to rupture the lysosomal membrane by using ordinary detergents, since they are indiscriminate as to membrane type and will attack the cell membrane first. This basic impediment was overcome in designing the compounds of the present invention by taking advantage of the difference between the intralysosomal pH and pH of the cell interior environment, i.e., of the cytosol or intercellular fluid. This difference amounts to from 2 to 4 pH units.
More specifically, the weekly basis amines or nitrogen-containing heterocyclic compounds of the present invention have a pK value of from 3.5 to 8, hereby they become substantially protonated inside, but not outside of the lysosomes, due to the pH difference between the lysosome and the remainder of the cell. Protonation gives the compound the hydrophilic portion of its molecular structure, and since it already possesses a lipophilic portion, it becomes, at that point, a lysosomotropic detergent. The protonated species, which is ionized, is thermodynamically more stable within the lysosome than in the cytosol, and so will accumulate there, until its concentration is as much as 1000 times that in the cytosol. Also, the ionization of the compound inhibits its passing out through the lysosomal membrane.
The lysosomotropic detergent accumulates in the bilayer of the lysosomal membrane, which gradually weakens, breaking up when some point related to the critical micelle concentration of the protonated species is reached.
The weakly basic amine and nitrogen-containing heterocyclic compound lysosomotropic detergents of the present invention have utility in several therapeutic areas as a result of their ability to rupture the lysosomal membrane, as described above.
For example, the compositions of the present invention have anti-fertility, i.e., contraceptive activity through their ability to interfere with the functioning of the specialized lysosome of the sperm cell, which is called the acrosome.
2. Brief Description of the Prior Art
The concept of lysosomotropic drugs was originated by (1) De Duve et al., Biochem. Pharmacol., 23, 2495 (1974), and has been applied to the treatment of leukemia using DNA complexes of adriamycin and daunorubucin; (2) Trouet et al., Nature (London), New Biol., 29, 110 (1972); and (3) Trouet et al., Eur. J. Cancer, 10, 405 (1974).
Compounds useful in the compositions and methods of the present invention are described in a number of publications, none of which, however, describe or suggest the particular use in which these compounds have been put in the present invention. Reference is made, for example, to the following such publications: (4) Wibaut et al., Rec. Trav. Chim., 72, 513 (1953); (5) Shelton et al., U.S. Pat. No. 2,446,792; (6) Techitchibabine, Bull. Soc. Chim., 5, 429 (1938); (7) Wibaut, Rec. Trav. Chim., 63, 141 (1944); (8) King et al., J. Econ. Entomol., 37, 629 (1944); (9) Birchenough, J. Chem. Soc., 1951, 1263; (10) Knight et al., J. Chem. Soc., 1938, 682; (11) Niederl et al., U.S. Pat. No. 2,602,791; (12) Niederl et al., JACS, 70, 618; (13) Gitterman et al., U.S. Pat. No. 3,718,651; and (14) Shen et al., U.S. Pat. No. 3,840,542;
Compounds related to the novel weakly basic amine compounds of the present invention are described in (15) Foulletier et al. U.S. Pat. No. 4,059,629; (16) Brown U.S. Pat. No. 3,214,412; and (17) Husted U.S. Pat. No. 2,727,923. However, none of these patents describe or suggest the particular amines of the present invention, which must be 2,2-difluoro- or 2,2,2-trifluoroethyl, and thus have a methylene bridge between the flourinated methyl electron-withdrawing group and the nitrogen atom.
Husted, for example, teaches a methylene bridge, but only in association with a fluorinated alkyl group of at least 3 carbon atoms. For each amines to be useful in the compositions of the present invention, they must have an ethylene bridge separating the fluorinated alkyl group from the nitrogen atom. Further, Husted does not disclose the lipophilic alkyl substituent of 8 to 30 carbon atoms.
Brown teaches only difluoromethylamines.
Foulletier discloses compounds useful in the compositions of the present invention, but does not teach the novel amine compounds of the present invention. Thus, Foulletier discloses only 3,3,3-trifluoropropylamine, rather than 2,2difluoro- or 2,2,2-trifluoroethylamine.
As will be shown in more detail below, the related amine compounds of the prior art do not possess properties sufficient for use in the compositions and methods of the present invention.